U.S. patent number 4,235,786 [Application Number 06/080,939] was granted by the patent office on 1980-11-25 for process for producing oil-soluble derivatives of unsaturated c.sub.4 -c.sub ..
This patent grant is currently assigned to Exxon Research & Engineering Co.. Invention is credited to Max J. Wisotsky.
United States Patent |
4,235,786 |
Wisotsky |
November 25, 1980 |
Process for producing oil-soluble derivatives of unsaturated
C.sub.4 -C.sub .
Abstract
An improved process for preparing oil-soluble derivatives of
unsaturated C.sub.4 -C.sub.10 dicarboxylic acid materials, e.g. the
product of the reaction of polyisobutylene and maleic anhydride,
under Ene reaction conditions characterized in that said Ene
reaction is conducted under acidic conditions as by conducting said
reaction in the presence of from 0.01 to 5 wt. %, based on total
weight of the reactants, of an oil-soluble strong organic acid
containing a hydrogen dissociating moiety which has a pK of less
than about 4.0, as exemplified by a C.sub.15 to C.sub.76
hydrocarbyl-substituted sulfonic acid, whereby sediment resulting
from said Ene reaction is markedly reduced to less than 1 wt.
%.
Inventors: |
Wisotsky; Max J. (Highland
Park, NJ) |
Assignee: |
Exxon Research & Engineering
Co. (Florham Park, NJ)
|
Family
ID: |
22160629 |
Appl.
No.: |
06/080,939 |
Filed: |
October 1, 1979 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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967276 |
Dec 7, 1978 |
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Current U.S.
Class: |
549/255; 560/203;
562/595 |
Current CPC
Class: |
C07C
57/13 (20130101); C08F 8/46 (20130101); C08F
110/10 (20130101); C08F 8/46 (20130101) |
Current International
Class: |
C07C
57/00 (20060101); C07C 57/13 (20060101); C08F
8/00 (20060101); C08F 8/46 (20060101); C07D
307/60 () |
Field of
Search: |
;260/346.74 ;560/203
;562/595 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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F 10267 |
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Sep 1956 |
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DE |
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1337724 |
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Nov 1973 |
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GB |
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Primary Examiner: Jiles; Henry R.
Assistant Examiner: Dentz; Bernard
Attorney, Agent or Firm: Mahon; John J.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of Ser. No. 967,276,
filed Dec. 7, 1978 now abandoned.
Claims
What is claimed is:
1. An improved process for preparing oil-soluble derivatives of a
monoethylenically unsaturated C.sub.4 -C.sub.10 dicarboxylic acid,
anhydride or ester comprising the Ene reaction of said unsaturated
C.sub.4 -C.sub.10 dicarboxylic acid, anhydride or ester and an
olefin containing from 30 to 700 carbons characterized in that said
Ene reaction is carried out in the presence of at least a
sediment-reducing amount of an oil-soluble, strong organic acid,
having a pk less than about 4, and said acid is of the class
consisting of hydrocarbyl substituted phosphorous containing acids,
hydrocarbyl substituted maleic acids, hydrocarbyl substituted
malonic acids, hydrocarbyl substituted sulfuric acids, hydrocarbyl
substituted sulfonic acids and hydrocarbyl alpha-substituted
carboxylic acids wherein the alpha substituent or substituents is
selected from the group consisting of nitrilo or nitro, said
hydrocarbyl substituents having at least 15 carbons.
2. An improved process according to PG,19 claim 1 wherein said
olefin is polyisobutylene and said dicarboxylic acid, anhydride or
ester is maleic anhydride.
3. An improved process according to claim 1 wherein said acid is an
oil-soluble sulfonic acid having a hydrocarbyl substituent
containing from 15 to 70 carbons.
4. An improved process according to claim 3 wherein said
dicarboxylic acid anhydride is maleic anhydride, said olefin is
poly(isobutylene) and said sulfonic acid is present in an amount of
from 0.01 to 5 wt.% based on the total weight of said reactants and
is an alkaryl sulfonic acid containing from 24 to 40 total carbon
atoms per molecule.
5. An improved process according to claim 4 wherein said acid is an
alkylated benzene sulfonic acid having a number average molecular
weight ranging from 475 to 600.
6. An improved process according to claim 1 wherein the olefin is a
C.sub.2 -C.sub.5 monoolefin homopolymer.
7. An improved process according to claim 1 wherein the olefin is a
copolymer of two or more C.sub.2 -C.sub.5 monoolefins.
8. An improved process according to claim 1 wherein the olefin is a
copolymer of a C.sub.2 -C.sub.5 monoolefin with a minor amount of a
C.sub.4 -C.sub.18 nonconjugated diolefin.
9. An improved process according to claim 1 wherein the olefin is
ethylene.
10. An improved process according to claim 6 wherein the olefin is
propylene.
11. An improved process according to claim 6 wherein the olefin is
butylene.
12. An improved process according to claim 6 wherein the olefin is
pentene.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to high temperature process, i.e. an "Ene"
process, for producing oil-soluble derivatives of a
monoethylenically unsaturated C.sub.4 -C.sub.10 dicarboxylic acid
material under conditions of reduced sediment formation as well as
to the resulting substantially sediment-free product useful for
preparing ashless dispersants untilized in lubricating oil and fuel
compositions. In particular, this invention is directed to a
sediment-free process involving the "Ene" reaction of a polyolefin
and maleic anhydride to provide a precursor for the production of
lubricating oil and fuel additives wherein said reaction is carried
out in the presence of a sediment-preventing amount of an
oil-soluble strong organic acid.
2. Description of the Prior Art
During the past several decades, ashless sludge dispersants have
become increasingly important, primarily in improving the
performance of lubricants in keeping the engine clean of deposits
and permitting extended crankcase oil drain periods while avoiding
the undesirable environmental impact of the earlier used
metal-containing additives. Most commercial ashless dispersants
fall into several general categories.
In one category, an amine or polyamine is attached to a long-chain
hydrocarbon polymer (the oil-solubilizing portion of the molecule),
usually polyisobutylene, through an acid group, such as a
dicarboxylic acid material, e.g. succinic anhydride, by forming
amide or imide linkages.
In a second category, an alkanol or polyol is attached to said
long-chain hydrocarbon polymer through said acid by forming an
ester linkage.
In yet another category, the reacton products of
hydrocarbon-substituted succinic anhydride, e.g.
polyisobutenylsuccinic anhydride, with compounds containing both an
amine group and a hydroxy group have been suggested as useful or
investigated in the prior art.
The common reactant in all said categories is the long-chain
hydrocarbon polymer attached to a dicarboxylic acid group. The
polyolefin diacid is readily obtained via the dehydrohalogenation,
Diels-Alder or "Ene" reaction of an olefin or a chlorinated olefin
with an unsaturated C.sub.4 to C.sub.10 dicarboxylic acid,
anhydride or ester thereof, such as fumaric acid, itaconic acid,
maleic acid, maleic anhydride, dimethyl fumarate, etc. The
dicarboxylic acid material formed via the Ene reaction of an olefin
with maleic anhydride results in an alkenyl-substituted anhydride
which may contain a single alkenyl radical or a mixture of alkenyl
radicals variously bonded to the cyclic succinic anhydride group.
This "Ene" product is a preferred precursor for said ashless
dispersants since it does not contain any halogen which could be a
source of undesired activity when said dispersant is incorporated
into the lubricant or fuel.
Unfortunately, the "Ene" reaction of an olefin and maleic anhydride
is difficultly reactable and/or results in extensive sediment
formation believed to be primarily poly(maleic anhydride) and
decomposition products of maleic anhydride.
The deleterious effect of metal ion and alkyl amine contamination
upon molten maleic anhydride has been reported, by Vogler et al in
the "Journal of Chemical and Engineering Date", Vol. 8, No. 4, pgs.
620-623 of October 1963 entitled "Effect of Contaminants on the
Thermal Stability of Maleic Anhydride", to include heat and gas
evolution and a solid polymeric material. The structure of
poly(maleic anhydride) was the subject of a paper by R. Bacskai,
which appeared in the "Journal of Polymer Science", Vol. 14,
1797-1806 (1976) and which teaches that polymerization can be
initiated with free radical catalysts and results in the evolution
of CO.sub.2. The "Ene" reaction of olefins having from 12 to 18
carbons with maleic anhydride to prepare alkenyl succinic anhydride
has been conducted in the presence of inorganic acids, anhydrides
and salts thereof such as boron phosphate (see German Patent
Application No. F 10267 IV b/12 published Sept. 6, 1956).
Another "Ene" reaction of olefins having 6 to 24 carbons with
maleic anhydride to prepare said alkenyl succinic anhydrides is
carried out in the presence of phosphorous containing sequestrants
and hydroxy aromatic compounds for the preparation of detergents of
improved color, i.e. reduced colored polymeric byproducts.
The suppression of polymeric byproducts arising out of the Ene
preparation of alkenyl succinic anhydrides is reported in U.S. Pat.
No. 3,819,660 to be achieved by the presence in the reactor of a
C.sub.1 to C.sub.3 alkyl-substituted benzene sulfonic acid
(preferably as a solute in acetic anhydride) and in U.S. Pat. No.
4,086,251 by the presence in the reactor of a halogen-containing
additive.
Thus, the prior are teaches the "Ene" preparation of alkenyl
succinic anhydrides but unfortunately with excessive sediment
formation, which sediment appears to be at least in part
deleterious poly(maleic anhydride). Further, some of catalysis
scavengers and sequestrants which are used in the preparation of
alkenyl succinic anhydrides are detrimental for lubricating oil
applications in that solid materials are corrosive and/or are
oil-insoluble thus contributing to haze and/or sediment.
It is therefore an object of this invention to produce alkenyl
succinic anhydrides by the Ene process with reduced sediment
formation through the influence of a lubricating oil-soluble
material.
SUMMARY OF THE INVENTION
It has been discovered that sediment formation in the "Ene"
reaction of an olefin with maleic anhydride can be markedly reduced
by the presence of a sediment-reducing amount of an oil-soluble
strong organic acid.
Thus the sediment formation problem of said prior art "Ene"
processes can be overcome by incorporating into said process
environment a sediment-reducing amount e.g. 0.01 to 5 wt.% of an
oil-soluble strong organic acid, said acid containing a hydrogen
dissociating moiety which has a pK of from -10 to +4, preferably
ranging from about -3 to +2 based upon the dissociation of the acid
in water.
This invention caan be characterized then as a process for the
preparation of a hydrocarbon-soluble C.sub.30 -C.sub.700
hydrocarbyl substituted C.sub.4 -C.sub.10 dicarboxylic acid
material, preferably C.sub.50 -C.sub.120 olefin substituted
succinic anhydride, comprising the step of reacting said olefin
with said dicarboxylic acid material, for example polyisobutylene
with maleic anhydride, in a mole ratio of 0.5 to 3, preferably 1 to
2, of olefin to dicarboxylic acid material in the presence of a
sediment-reducing amount, generally from 0.01 to 5, preferably 0.05
to 2.5, wt.%, of an oil-soluble strong organic acid, preferably a
C.sub.15 -C.sub.70 optimally C.sub.28 -C.sub.36 hydrocarbyl
substituted sulfonic acid, said wt.% based upon the total weight of
the reactants. The reaction temperature ranges from about 150-260,
preferably 195.degree.-235.degree. C. for a period of from 1-24
hours, preferably 2-14 hours, optimally from 8-10 hours and under a
pressure ranging from atmospheric to an elevated pressure of 500
kpa.
The result of carrying out the process of the invention is that one
obtains a reaction product having a materially reduced sediment
content. In addition, a reduced reaction time is obtained since it
is possible to go to higher reaction temperatures. It is essential
to use the oil-soluble strong organic acids: since they are soluble
in the olefin reactant which in turn results in a uniform
distribution of the acids throughout the reactor and thus avoids
localized sediment formation arising out of maldistribution of the
organic acid; and, also soluble in the lubricating oil composition
even though derivatized along with the alkenyl succinic anhydride
during the latter's subsequent derivatization, e.g. reaction with
an alkylene polyamine to provide an alkenyl succinimide. It appears
that utilization of an oil-soluble organic acid with a pK of less
than about 4.0 prevents the sediment formation which is primarily
poly(maleic anhydride) either through the mechanism of maintaining
the acid pH during the reaction mixture and/or deactivation of
metallic ions such as sodium or similar metallic ions which are
reported to provoke formation of the poly(maleic anhydride).
DETAILED DESCRIPTION OF THE INVENTION
The product of the inventive process as indicated above is a
hydrocarbon-substituted dicarboxylic acid material conventionally
considered usually as an olefin diacid. The hydrocarbon substituent
chain length generally determines the hydrocarbon solubility of the
resulting diacid and the dispersants made therefrom. It is for this
reason that we are concerned in this invention with the preparation
of diacids having hydrocarbon substitutents ranging from 30-700
carbon atoms, more usually from 36-170. The hydrocarbon substituent
can be considered substantially saturated.
The substantially saturated hydrocarbyl substituted diacid material
includes diacids, estes and anhydrides as well as imides and amides
serived from ammonia or a lower primary amine and also mixtures of
such compounds.
In general, these hydrocarbyl substituted dicarboxylic acid
materials, preferably alkenylsuccinic anhydrides, and their
preparation are well known in the art, for example, see U.S. Pat.
Nos. 3,219,666; 3,172,892; 3,272,746; as well as being commercially
available, e.g., polyisobutenyl succinic anhydride.
Preferred olefin polymers for reaction with the unsaturated
dicarboxylic acids are polymers comprising a major molar amount of
C.sub.2 to C.sub.5 monoolefin, e.g., ethylene, propylene, butylene,
isobutylene and pentene. The polymers can be homopolymers such as
polyisobutylene, as well as copolymers of two or more of such
olefins such as copolymers of: ethylene and propylene; butylene and
isobutylene; propylene and isobutylene; etc. Other copolymers
include those in which a minor amount of the copolymer monomers,
e.g., 1 to 20 mole % is a C.sub.4 to C.sub.18 nonconjugated
diolefin, e.g., a copolymer of isobutylene and butadiene; or a
copolymer of ethylene, propylene and 1,4-hexadiene; etc. The olefin
polymers may contain cycloalkyl and aromatic groups.
The olefin polymers providing the oil-solubilizing groups will
usually have number average molecular weights (M.sub.n)s ranging
from 400 to 10,000 or from about 30 to about 700 carbons, more
usually 500 to 2400 or about 36 to 170 carbons, preferably 700 to
1700 or about 50 to 120 carbons, optimally 800 to 1600 or about 60
to 110 carbons with approximately one terminal double bond per
polymer chain. An especially valuable starting material for a
highly potent dispersant additive are polyalkenes, e.g.,
polyisobutylene, having about 70 carbons.
The polycarboxylic acid anhydrides are obtained by dehydrating the
corresponding acids. Dehydration is readily accomplished by heating
the acid to a temperature above about 70.degree. C., preferably in
the presence of a dehydration agent, e.g. P.sub.2 O.sub.5. Cyclic
anhydrides are usually obtained from polycarboxylic acids having
the acid radicals separated by no more than three carbon atoms,
such as substituted succinic or glutaric acids, whereas linear
polymeric anhydrides are obtained from polycarboxylic acids having
the acid radicals separated by four or more carbon atoms.
The process of the invention, which may be conducted in batch,
staged or continuous reactors, is preferably run in a pressure
vessel wherein said olefin is first introduced and thereafter the
acid material introduced in a staged manner into a melt of said
olefin to which has first been added the desired amount of
oil-soluble organic acid. The reactants are continually stirred. It
is convenient to introduce the oil-soluble organic acid as a
solution of acid and oil which facilitates its distribution through
the heated liquid alpha-olefin.
Suitable times of reaction will generally be in the range from 1 to
24 hours, temperatures will usually be in the range of 150.degree.
C. to 260.degree. C., preferably 190.degree. C. to 250.degree. C.,
most preferably 195.degree. C. to 235.degree. C. and pressures from
atmospheric to 50 psig are generally used. Acid feed to the reactor
per 100 parts by weight of olefin may be in the range of: 4 to 30,
preferably 6 to 15 parts by weight, preferably added in a staged
manner involving from 20 to 50, % of the total acid charge with
each stage normally uniformly distributed over the reaction time. A
sediment-reducing amount of oil-soluble acid has been found to be
at least 0.01, preferably 0.05 to 2.5, optimally 0.1 to 1.0, wt.%
(based on the total weight of the reactant charge).
Any oil-soluble strong organic acid can be used in accordance with
this invention, said acid containing a hydrogen dissociating moiety
which has a pK of -10 to about +4.0, preferably from about -3 to
about +2. The term pK for the purpose of this disclosure is used
herein to express the aqueous dissociation of the acid used to
inhibit the sediment formation which is provoked by thermal and/or
cationic catalysis of the polymerization of the polycarboxylic acid
material under "Ene" reaction conditions. Thus, pK can be defined
as the negative logarithm to the base 10 of the equilibrium
constant for the dissociation of the oil-soluble organic acid. For
the purposes of this invention, the strong acids have a pK of up to
about 4.0 and optimally ranges from about -3 to about +2 whereas
the weak acid which fails to inhibit sediment formation has an acid
moiety providing a pK of more than about 4.8, usually in the range
of 5 to 8 and can be represented by stearic acid.
As used herein, oil-soluble is defined as those organic acids which
themselves are substantially soluble in mineral oil at 20.degree.
C. to at least 50 wt.%.
Representative classes of the oil-soluble strong organic acids are
represented by maleic acid, malonic acid, phosphoric acid,
thiophosphoric acids, phosphonic acid, thiophosphonic acids,
phosphinic acid, thiophosphinic acids, sulfonic acid, sulfuric
acid, and alpha-substituted or nitrilocarboxylic acids wherein the
oil-solubilizing group or groups are hydrocarbyl and containing
from 15 to 76, preferably from 24 to 40, optimally 28 to 36, total
carbon atoms.
Particularly preferred for use in this invention for inhibiting
sediment formation are the oil-soluble sulfonic acids which are
typically alkaryl sulfonic acids. These sulfonic acids are
typically obtained by the sulfonation of alkyl substituted aromatic
hydrocarbons such as those obtained from the fractionation of
petroleum by distillation and/or extraction or by the alkylation of
aromatic hydrocarbons as, for example, those obtained by alkylating
benzene, toluene, xylene, naphthalene, diphenyl and the halogen
derivatives such as chlorobenzene, chlorotoluene and
chloronaphthalene. The alkylation may be carried out in the
presence of a catalyst with alkylating agents having from 9 to
about 70 carbon atoms such as, for example, haloparaffins, olefins
that may be obtained by dehydrogenation of paraffins, polyolefins
as, for example, polymers from ethylene, propylene, etc. Preferred
sulfonic acids are those obtained by the sulfonation of
hydrocarbons prepared by the alkylation of benzene or toluene with
tri-, tetra- or pentapropylene fractions obtained by the
polymerization of propylene. The alkaryl sulfonic acids contain
from 9 to 70, preferably from 18 to 34, optimally from 22 to 30,
carbon atoms per alkyl substituent(s) in the aryl moiety as
illustrated by the formula ##STR1## contains from 9 to 70 carbons,
etc. Particularly preferred is an alkylated benzene sulfonic acid
having a molecular weight (M.sub.n) of from 475 to 600 and an
average of 2 alkyl groups wherein each of said groups contain an
average of 11 to 15 carbons.
The alkylated benzene from which the sulfonic acid is prepared is
obtained by known alkylation processes; benzene being generally
reacted with such alkylating agents as isobutylene, isoamylene,
diisobutylene, triisobutylene, etc., or olefin-containing mixtures
containing from refinery gases. Boron trifluoride is a preferred
alkylating agent.
Among the C.sub.9 -C.sub.70 alkylated benzenes which are preferably
employed in the preparation of the sulfonic acid are
p-isopropylbenzene, p-amylbenzene, isohexylbenzene, p-octylbenzene,
nonylbenzene, ditertiaryoctylbenzene, waxy alkylated benzenes,
benzenes alkylated with suitable branched chain polymers of up to
70 carbons obtained from propylene, butylene, amylene or mixtures
thereof or the like. Optimally, nonyl or dodecyl or either of their
equivalents in a mixture of alkyls is employed in preparation of
the sulfonic acid.
The oil-soluble phosphorous-containing acids can be represented by
the following general formulae:
______________________________________ (1) R'ZPOZ.sub.2 H
phosphoric or thiophoshoric (2) (R'Z)PZ.sub.2 H acids, (3)
(R').sub.2 PZ.sub.2 H phosphinic or thiophosphinic acids; and, (4)
R'POZ.sub.2 H phosphonic or thiophosphonic acid
______________________________________
wherein R' is one or two (same or different) C.sub.9 -C.sub.70
hydrocarbyl radicals such as alkyl, aryl, alkaryl, aralkyl, and
alicyclic radicals to provide the required oil solubility with a
total carbon content of 15 to 70 carbons, O is oxygen and Z is
oxygen or sulfur. The acids are usually prepared by reacting
P.sub.2 O.sub.5 or P.sub.2 S.sub.5 with the desired alcohol or
thiol to obtain the substituted phosphoric acids. The desired
hydroxy or thiol compound should contain hydrocarbyl groups of from
about 9 to about 70 carbon atoms with at least 15 total carbon
atoms average to provide oil solubility to the product. Examples of
suitable compounds are hexyl alcohol, 2-ethylhexyl alcohol, nonyl
alcohol, dodecyl alcohol, stearyl alcohol, amylphenol, octylphenol,
nonylphenol, methylcyclohexanol, alkylated naphthol, etc., and
their corresponding thio analogues; and mixtures of alcohols and/or
phenols such as isobutyl alcohol and nonyl alcohol; orthocresol and
nonylphenol; etc., and mixtures of their corresponding thio
analogues.
In the preparation of the hydrocarbyl substituted thiophosphoric
acids, any conventional method can be used, such as, for example,
the preparation described in U.S. Pat. No. 2,552,570; 2,579,038 and
2,689,220. By way of illustration, a dialkaryl substituted
dithiophosphoric acid is prepared by the reaction of about 2 moles
of P.sub.2 S.sub.5 with about 8 moles of a selected alkylated
phenol, e.g. a mixture of C.sub.8 -C.sub.12 alkyl substituted
phenols, i.e. nonyl phenol, at a temperature of from 50.degree. C.
to 125.degree. C. for about 4 hours. In the preparation of
hydrocarbyl substituted thiophosphinic acids as conventionally
known, a disubstituted phosphine is oxidized to give disubstituted
thiophosphinic acids (see F. C. Whitmore's Organic Chemistry
published by Dover Publications New York, N.Y. (1961) page 848). A
highly useful organo-phosphorous-containing acid is commercially
available as Tiger Acid from E. I. duPont and believed to be
tridecyl mono/dihydrogen phosphoric acid containing an average of
16 to 26 carbons.
Particularly preferred for preparation of oil-soluble phosphoric,
phosphonic and phosphine acids useful in the process of the
invention are mixed aliphatic alcohols obtained by the reaction of
olefins of carbon monoxide and hydrogen and substituted
hydrogenation of the resultant aldehydes which are commonly known
as "Oxo" alcohols, which Oxo alcohols for optimum use according to
this invention will contain an average of about 13 carbon atoms.
Thus for the purposes of this invention a di-C.sub.13 Oxo
phosphoric acid which has an acid dissociating moiety with a pK of
about 2.0 is preferred. The oil-soluble phosphorous-containing
acids are readily prepared from these alcohols by reaction with
P.sub.2 O.sub.5 as is well known in the art.
Another class of useful sediment-inhibiting agents are oil-soluble
hydrocarbyl substituted maleic acids of the general formula
##STR2## wherein R" is an oil-solubilizing, hydrocarbyl group
containing from 15 to 70 carbons. Representative of these
oil-soluble maleic acid derivatives are pentadecylmaleic acid
(1,2-dicarboxyl pentadecene-1), hexadecylmaleic acid, eicosylmaleic
acid, triacontanylmaleic acid, polymers of C.sub.2 -C.sub.5
monoolefins having from 15 to 70 or more carbons substituted onto
said maleic acid, etc.
Additional sediment-inhibiting agents are oil-soluble hydrocarbyl
containing from 15 to 70 carbons, substituted malonic acid of the
general formula
wherein R" has the meaning set forth above as an oil-solubilizing
hydrocarbyl group which is illustrated by the following
representative compounds which include the malonic acid
counterparts of the above-referenced hydrocarbyl substituted maleic
acids, i.e. pentadecylmalonic acid, hexadecyl malonic acid,
etc.
Another class of sediment-inhibiting agents are oil-soluble
hydrocarbyl containing from 15 to 70 carbons, substituted sulfuric
acids of the general formula R"HSO.sub.4 wherein R" has the meaning
set forth above as an oil-solubilizing group which is represented
by the following compounds which include pentadecylsulfuric acid;
hexadecylsulfuric acid, eicosylsulfuric acid, triacontanylsulfuric
acid, etc.
A further group of strong acids which can be used in accordance
with the invention to inhibit sediment formation are oil-soluble
mono- and di-.alpha.-substituted hydrocarbyl carboxylic acids
having the general formula: ##STR3## where R" is a C.sub.15
-C.sub.70 hydrocarbyl, oil-solubilizing group as referenced above
and X refers to hydrogen, nitrilo or nitro group. These materials
are represented by the following: .alpha.-nitro and
.alpha.,.alpha.-di-nitro, substituted acids such as dodecanoic,
pentadecanoic, octadecanoic, docosanoic, octacosanoic,
tricontanoic, tetracontanoic, pentacontanoic, hexacontanoic,
heptacontanoic, etc.
The following examples illustrate more clearly the process of the
present invention. However, these illustrations are not to be
interpreted as specific limitations of this invention.
EXAMPLE 1
125 pounds of polyisobutylene having a number of average molecular
weight (M.sub.n) of about 900 (carbon chain lengths of 35 to 100
carbons) and a specific viscosity @ 100.degree. C. of 210 was
charged to a 30-gallon glass-lined reactor equipped with a stirrer
and adapted to be closed. To this reactor was then added 0.35
pounds of a mineral oil solution containing 50% by weight of an
alkylated benzene sulfonic acid having an (M.sub.n) of 500 and
containing an average of about total 30 carbons). The resulting
mixture was stirred while heating to 120.degree. C. under a vacuum
of about 600 mm. Hg and held at 120.degree. C. for 1 hour. While
maintaining at 120.degree. C. and after returning to ambient
pressure, 13.2 pounds of maleic anhydride was added and the
reaction vessel sealed. The system was heated to 235.degree. C. and
with the pressure maintained at about 150 kilo pascals (1.36
atmospheres), kept at 235.degree. C. for 6 hours. The vessel was
then opened and the system sparged with N.sub.2 at 235.degree. C.
for 2 hours.
The resulting product had a kinematic viscosity @ 100.degree. C. of
603.6 centistokes with 0.2% sediment (measured by a test in which
50 ml of heptane and the solution placed in a calibrated tube prior
to centrifuging at about 1300 rpm for 20 minutes and thereafter
measuring the sediment in said calibrated tube).
EXAMPLE 2
The procedure of Ex. 1 was followed except that no sulfonic acid
was present.
The resulting product had a kinematic viscosity @ 100.degree. C. of
397.5 centistokes and 3.0% sediment. It is thus apparent that the
presence of about 0.13 wt.% of an acid reduced the sediment
formation by 93%.
EXAMPLE 3
In laboratory scale preparations of polyisobutenyl succinic
anhydride, a number of acids are hereinafter shown to markedly
reduce sediment formation normally formed in the "Ene" reaction of
polyisobutylene and maleic anhydride.
In each of the reactions, 250 grams polyisobutylene is reacted with
13.8 grams of maleic anhydride in the presence of 0.1 gram of
silicone antifoamant by heating the polyisobutylene to
193.degree.-198.degree. C. under a nitrogen blanket for about 1
hour and then adding the maleic anhydride and antifoamant and as
desired acid and thereafter raising the temperature to
230.degree.-235.degree. C. followed by reflux for 4 hours and then
cooling with nitrogen stripping.
The results of some of the runs are hereafter set forth in the
table and show that oil-soluble strong organic acids reduce the
sediment and further confirm the optimum utility of alkylated
benzene sulfonic acid containing an average of about 30 total
carbons and having a (M.sub.n) of about 500.
Example 3-D confirms the reported observations (see Vogler et al
reported in Description of Prior Art) that the presence of alkali
ions such as sodium (Na.sup.+) markedly increases sediment
formation.
One important use for the oil-soluble alkenylsuccinic anhydride
products, those whose alkenyl substituent have (M.sub.n) in the
range of about 400 to 10,000, usually 500 to 2500, is through their
alkenyl succinimides of ethylene diamine, diethylene triamine,
triethylene tetraamine and tetraethylene pentamine as dispersant
additives for lubricating oils. Similarly useful are the polyol
esters, preferably pentaerythritol esters, of the oil-soluble
alkenylsuccinic anhydrides. Since the sediment-reducing additive of
the invention is oil-soluble as well as being soluble in the
alkenylsuccinic anhydride, it need not be removed though it must
not become oil-insoluble upon derivatization or because of
incompatibility with other additive components or contain moieties
such as a chloro substituent that would adversely effect the
performance of the lubricating oil.
The inorganic acids are disadvantageous since they are not soluble
in the reactants making them difficult to distribute uniformly
through the reactant mix and generally corrosive to the reactor and
environmentally dangerous to contain and dispose of and/or add to
the burden of separating the reactor mix from the alkenylsuccinic
anhydride product.
The oil-insoluble organic acids add as well to the burden of
removing additional material from the product but also present a
potential hazing material in the formulated lubricating oil.
The halogen-containing acids, particularly those containing
chlorine, are corrosive both to the reactor and to the machine
using the lubricating oil formulated with the alkenylsuccinic
product or its derivative.
The invention in its broader aspect is not limited to the specific
details shown and described and departures may be made from such
details without departing from the principles of the invention and
without sacrificing its chief advantages.
______________________________________ Sediment Polyisobutylene
Acid Resulting Run No. (--Mn) Type Wt.% Wt.%
______________________________________ 3A 900 -- 0 1.8 3B 900
alkylbenzene 0.4 0.2 sulfonic acid.sup.1 3C 900 alkylbenzene 0.1
0.4 sulfonic acid.sup.1 3D 900 NaHSO.sub.4 0.3 3.0 3E 900 tridecyl
mono/ 0.2 0.8 diacid phosphate.sup.2 3G 1300 -- 0 1.0 3K 1300
alkylbenzene 0.2 0.08 sulfonic acid.sup.1 3N 1300 alkylbenzene 0.2
0.16 sulfonic acid.sup.1 ______________________________________
.sup.1 an alkylbenzene sulfonic acid having a (--Mn) of about 530
and containing an average total carbon content of about 30 carbons.
.sup.2 Tiger Acid sold by the Petroleum Div. of E. I. duPont,
Wilmington, Delaware and believed to have at least 16 average
carbon content per molecule.
* * * * *